________________________________________________________________________

http://www.union-ic.com Rev.06 Apr.2015

1/14

UM809/810

3-Pin Microprocessor Reset Circuits

UM809/810 SOT323/SOT23-3

General Description

The UM809/810 series are ultra low current, cost effective system supervisory circuits designed to

monitor the power supplies in digital systems. They provide a reset signal to the host processor

when necessary, offer excellent circuit reliability & low cost by eliminating external component

and adjustment when used with +5V, +3.3V, +3.0V or other voltage powered circuits.

The reset output is driven active within 10µs of power supply falling through the reset voltage

threshold. Reset is keeping active for a minimum of 140ms after system power supply has risen

above the reset threshold. Reset threshold suitable for operation with variety of supply voltage are

available.

UM809 has an active-low reset output while UM810 has an active-high reset output. The

UM809/810 are optimized to reject fast transient glitches on the power supply line, and the reset

Each of these ICs consists of a voltage reference comparator, resistors for detector threshold

setting, delay generator, output driver & hysteresis circuit. The reset threshold & time delay are

fixed with high accuracy internally and does not require any external adjustment.

devices are available in 3 Pin SOT323 or SOT23 packages.

Applications

Features



CPU and Logic Circuit Reset



Power Fail Detectors



Computers



Embedded Systems



Battery-Powered Equipments



Intelligent Instruments



Wide Operation Voltage Range of 1V to 10V



Typical Quiescent Current of 3μA



No External Components



3-Pin Small SOT323 and SOT23 Packages







and 5.0V Supplies



Available in 2 Output Configurations

Push-Pull Low Active Reset Output (UM809)

Push-Pull High Active Reset Output (UM810)



Wide Operation Temperature: -40°C to +85°C

Pin Configurations

Top View

GND 1

RESET 2

(RESET)*

3 VCC

( )* for UM810

3

XXX

2

1

Marking Pin1

M: Month Code

UM809/810

SOT323/SOT23-3